Charles Spurgeon Commentary Isaiah 14:16-18

"They that see thee shall gaze at thee, they shall consider thee, [saying], Is this the man that made the earth to tremble, that did shake kingdoms; that made the world as a wilderness, and overthrew the cities thereof; that let not loose his prisoners to their home? All the kings of the nations, all of them, sleep in glory, every one in his own house." — Isaiah 14:16-18 (ASV)

That is, they lie in state, each one in the mausoleum of his family. They went down to death, and they were buried with all the honour and glory that were supposed to be due to their high position.